Conventional construction machinery (dozers, loaders, backhoes, skid steers, graders, etc) do not usually have cushioning suspension systems beyond the pneumatic tires included with some of this equipment. Thus, the machine ride can be very harsh when the terrain on which the vehicle travels is rough or uneven.
It is generally recognized that harshness of ride in construction machinery may be reduced via the use of suspension systems but only at a cost of lowered operational accuracy and efficiency. One major concern with suspension systems is the undesired motions that can result because of the addition of the systems as compared to a rigid mounted system. Thus, more sophisticated suspension systems are avoided as these systems tend to introduce vehicular height variations during work operations, causing inaccuracies and reducing work efficiencies.
An example of the height variations noted above is the vertical motion observed when a Semi-tractor trailer combination accelerates from a stop light. The forces from acceleration on these vehicles can, and often do, result in a twisting of the vehicle. Another example is the squat observed in the rear axle of automobiles with certain independent rear axle suspension systems. Such movements could be detrimental to the ability of a grading machine to perform its required tasks; squatting and twisting motions can cause changes in the position of a work tool such as, for example, a blade relative to the ground. Thus, the addition of suspension to a conventional work machine such as a grader can create a situation that improves vehicle ride but counters the operational efficiency of the machine by rendering a softness in the vehicle support and degrading the accuracy of blade movements.